Thick wall model daylight factor simulation


I am making a honeybee based tool to assess daylight factors in rhino. I managed to validate a thin-wall model with results from IES but when I try adding breadth to the walls (basically adding a sill and overhang to the window) my results in rhino diverge, with IES showing DF figures around 20% lower. I modeled the wall thickness as a shading geometry. All radiance parameters are the same between IES and Honeybee.

Any chance someone encountered this problem?

Is there a good way to account for the wall thickness when doing daylighting sims?


Ill just keep posting my issues here in hopes someone notices. I solved the thick wall issue by modelling the thick wall in rhino.

The question now is how was honeybee daylight factor results validated? I ran a honeybee calc and and an IES calc with the same parameters. On the attached images the grid is not really matching but you can see the divergence anyway. Some honeybee results are 100% better than ones from IES. Can anyone tell me why? Im not great at Radiance, but maybe there is a set of settings where results would converge?

forgot to add the picture


if the reflectance is the same in the IES and Honeybee model, there should be no big discrepancy. I don’t know how IES represents the geometry- it uses paper thin walls but has stand in geometry for daylight sims, I assume? - but am pretty sure that if you imported the IES model into GH, and ran it there with identical reflectances, the results would be near identical.



I agree with Max. Do you know which sky type does IES uses for calculating DF? It might be the difference between uniform and overcast skies. Honeybee let’s you to switch between the two but is using overcast as the default which is the CIE standard.

Also back to your question to automaye modeling wall thickness see this discussion:…